"When cultivating on water, we can't work with chemical products"

On 25 hectares De Kruidenaer cultivates herbs for the fresh market, from basil and mint to slightly less well-known species like lemon verbena and garlic chives. 3.5 hectares of herbs are grown in the greenhouse and on water, and the remaining 21.5 ha in foil tunnels and in the open field. Cultivation on water has many advantages, says Smits. "It is not only a clean cultivation method, but also a low-emission, residual-free and safe way of cultivation. In addition, this cultivation method is easy and provides a consistent quality of the product."

The herb growers cultivate basil and mint on water in the greenhouse. On water they cannot work with chemicals, Smits mentions. "The water in one pond always seeps through to another pond and the chemical products break down badly. In herb cultivation we are allowed to use very few chemical products. The waiting time is much longer than with other crops. We have been working with green crop protection for about five years: we started experimenting with it, and have expanded its use. By now we know pretty well what does and what does not work. Doing tests yourself, is the best way to learn.''

The advantage of green products is that you can harvest any time, Smits says. "Waiting times are very short." The cultivation of basil takes four weeks. The herbs are harvested in one go and then new plants are sown in the trays. The mint plant is a perennial plant, every six to seven weeks the twigs of mint are cut from the plant. "During the cutting, a small wound is made," the manager explains. "This wound is sensitive to Botrytis, especially if it stays wet for a long time and when the weather is dark. When it is sunny the wound will dry soon, and there is much less danger of a fungal infection." De Kruidenaer has been using Serenade for two years in order to fight Botrytis. A supplier of biological agents informed Smits about the product because of good results in strawberry cultivation. "Serenade has proven that it works," said the company manager. "Not only for the control of Botrytis, we also can use the product against mildew. But it is important that you use organic products preventively and maintain a tight spray schedule. We use Serenade weekly from August to the end of winter. We use a dosage of 5 liters/ha. We are satisfied with the results.''

The goal of De Kruidenaer is to use as little as possible or no chemical products at all in the future, says Smits. In the greenhouses, chemicals are already a thing of the past, but also in outdoor cultivation, the herb nursery wants to use biological products when and where it’s possible. Besides green crop protection, also plant stimulants and spore elements are used to increase plant resilience. "The advantage of these products is that you can mix them together," according to the company manager. It is important for him that the products are affordable. "That is a challenge for the manufacturers. Green crop protection must remain economically viable for regular cultivation.'' Smits expects that MRL demands from retail will become increasingly stringent in the future. De Kruidenaer is already responding to this by complying with the requirements of the Eco-labeled Vegetable Products. "As I mentioned, the residual limit in herbs is very low and we expect it to only go down further. The consumer is becoming increasingly environmentally conscious and is ever more often looking for clean products." But: "The same consumer has to follow the process of environmentally conscious cultivation," Smits concludes. "Now there's a zero tolerance for insects. If the consumer finds an insect on his twig of mint, they'll return it." With green crop protection, there is a chance that you may find an insect on your product. That's what the consumer has to learn to accept."